Crenadactylus ocellatus Gray 1845

Crenadactylus ocellatus (Gray, 1845)

South-western clawless geckos Figs. 4 A, 5, 6, 7

Diplodactylus ocellatus Gray, 1845

Synonymy: Diplodactylus bilineatus Gray, 1845 (fide Günther 1867) [‘South-west’ of Oliver et al. (2010)]

Holotype. BMNH 1947.3.6.68 from Western Australia. Specimen obtained from the Buchanan collection from WA, collection date not specified.

Synonomy. Diplodactylus bilineatus. Syntypes (2), Gray 1845, BMNH 1947.3.6.69 (2 specimens) from Houtman’s Abrolhos, Western Australia. Collected by ‘Mr. Gilbert’, collection date not specified.

Diagnosis. A moderately large (to 35.5 mm SVL) species of Crenadactylus with wide head (HW/HL 0.52– 0.70) and short trunk length (ILL/SVL 0.37–0.50). Rostral in full contact with nostril, internasal (if present) not extending beyond supranasal, 1 or 2 granular postmentals, dorsal scales homogeneous with smooth to weak keels, usually no pre-cloacal pores visible but some males with 2, when present pore-bearing scales in contact at midline, no enlarged tubercles on original tails. Ground colour tan and dark brown; dorsal pattern comprised of poorlydefined longitudinal pale and dark stripes, lateral zones pale with irregular dark stippling, pattern heavily overlain with intermixed pale and dark scales giving an irregular appearance, pale spots or ocelli comprised of 3–6 pale scales usually present in dorsolateral zone.

Description. A moderately built, small-bodied gecko (to 35.5 mm SVL); body elongate, oblong in crosssection; head relatively wide (HeadW/HeadL 0.52–0.71), moderately long (HeadL/SVL 0.27–0.33), moderately depressed (HeadD/HeadL 0.27–0.35); in dorsal view, widest at ear openings; head not distinct from neck with neck only weakly constricted; loreal region convex; snout moderately short (SnL/HeadL 0.32–0.40), tapering to rounded tip; head depth ~1.5–2 times eye diameter; eye moderately large; rostral ~2.5 times wider than high, in broad contact with nostril, dorsal edge concave to accommodate supranasals, rostral groove extends from dorsal edge of rostral to ~50% of rostral height; 0 or 1 small internasals; supranasals horizontally elongate, 2–3 times wider than long; nostrils small, similar in size to postnasals, directed laterally, in contact with rostral, supranasal, 2–4 postnasals and first supralabial; supralabials 7–9, antero-dorso edge of first supralabial in contact with nostril; second supralabial rectangular, wider than high, length equal to first supralabial; supralabials 3–5 slightly smaller than first and second, gradually decreasing in size, all wider than high; scales on crown small and slightly rounded, ~one-third the size of dorsal scales, increasing in size anteriorly onto snout and supraocular regions; scales on snout flat and slightly enlarged, 1.5–2 times larger than scales on crown; supraocular scales enlarged; 1 or 2 soft spines on posterior eyelid; mental triangular to trapezoidal in shape, widest anteriorly, not extending past ventral edge of first infralabial; postmental not enlarged relative to other scales adjacent to infralabials; gulars small near infralabials, decreasing to granular, ~0.1–0.2 the size of scales on ventrum, juxtaposed and slightly rounded; gulars flattened from mental to eye, becoming more rounded from eye to neck; infralabials 7–9, first largest and squareshaped, gradually decreasing in size posteriorly.

Limbs short, distance between limbs close to half of SVL (ILL/SVL 0.37–0.50); scales on anterior surfaces of forelimbs elongate, broad and rounded, slightly imbricate, decreasing in size distally, ~2 times the size of scales elsewhere on forelimb; scales on dorsal surface of hind limbs rounded and slightly raised, decreasing in size and becoming more rounded distally; scales on anterior surface of thigh flat and circular, slightly larger in area than scales on hindlimbs elsewhere; fingers 5; toes 5; claws absent from all digits, digits short; fourth finger lamellae in 6 rows; fourth toe lamellae in 8 rows; apical plates much wider than digit; two pairs of dorsal apical plates; one pair of ventral apical plates, round to ovate.

Scales on dorsum and lateral surfaces small and homogeneous, smooth to weakly keeled, ~2.5 times wider than deep, juxtaposed; scales slightly raised, highest point at posterior edge of scale, widest at midpoint of scale; scales on ventrum homogeneous, flat, imbricate, ~equal to 1.5 times the size of dorsal scales in area, widest at midpoint, with rounded posterior edge.

Tail moderately long, maximum width one-quarter to one-third along tail, gradually tapering to a fine point, round in cross-section; scales on dorsal surface of tail ~2–3 times size compared to dorsum, homogeneous, flattened, imbricate, square to oblong in shape, arranged in transverse rows; ventral tail scales flattened, ~2–3 times the size of dorsal tail scales; single enlarged cloacal spur per side, ~3–4 times the size of surrounding scales; no visible pre-cloacal pores (except on 2 males with 2 pores).

Colouration and pattern. Dorsal background colouration tan and dark brown; light brown dorsolateral lines edged with dark brown emanate from back of eye to tail, continues forwards past eye as pale canthal stripe, terminating above nostril; poorly-defined silver-grey vertebral stripe discernible in some specimens, 2–3 scales wide, bordered by poorly defined dark brown paravertebral lines or dark edges of dorsolateral lines; dorsolateral zone with 7–12 widely spaced ocelli between eye and tail, variably defined ocelli cluster comprised of 3–6 pale scales, often lacking or loosely bordered by darker scales; lateral zone with poorly-defined lateral line that extends from postero-ventral edge of eye above limbs to tail, continuing forward as dark loreal stripes to nostril; below lateral stripes on flanks a mixture of darkly pigmented scales with grey and pale scales; crown and snout a mixture of dark brown, brown and pale grey scales; supralabials pale with dark stippling, infralabials moderately pigmented; ventral edge of orbit dark brown; limbs have same intermixture of dark and pale scales with numerous scattered small pale ocelli, weak on front limbs, more prominent on rear; top of digits have a network of dark lines; ventrum pale with fine to heavy dark brown flecking, not forming conspicuous lines; heavier flecking on rear limbs and cloacal region and tail; tail continues dorsal pattern including ocelli on dorso-lateral stripes, dark vertebral zone and light brown paravertebral zone.

Distribution. This species occurs in the south-west of Australia (Fig. 2). It is absent from the mesic southwestern corner, extending only as far south-west as Waroona (WAM R88483) then extending eastwards including records from Kojanup, Tambelup and Fitzgerald River National Park. The western-most extent of the distribution is from an old record in Israelite Bay at Cape Arid National Park (WAM R14176) and a more recent record from Balladonia at the edge of the Nullarbor Plain (WAM R157901). It extends into the wheatbelt and to the arid interzone, with records from near Mount Manning and Bowgada Nature Reserves, and an isolated record from Walganna Rock in the north-east (WAM R135103, genotyped as C. ocellatus and shown in Fig. 3 A of Oliver et al. 2010). Occurs on most of the Houtman Abrolhos Islands (off Geraldton) on which surveys have been conducted. Habitat. Found in open woodland habitats throughout its range including areas dominated by Xanthorrhea grass trees, Eucalyptus (jarrah, mallee, marri, tuart, wandoo) and spinifex grass (Triodia) on a wide variety of soft (sandy and loamy) and hard stony substrates (e.g. laterite). Collectors’ notes record specimens have been found under ground cover such as fallen and rotten logs, woodpiles, leaf litter, granite boulders, limestone slabs, sheets of tin, railway sleepers and rubbish. One specimen (WAM R72276) was found one meter high under the bark of a gimlet tree, and other records mention ‘under bark’ indicating some climbing ability.

Etymology. The specific name ocellatus refers to the pale scattered blotches or ‘ocelli’ on the dorsum.

Remarks. Our experience with this species indicates they are reasonably common compared to other Crenadactylus species. Within the genus, C. ocellatus is exceptional for its dorsal patterning, with its intermixture of dark and pale scales and less well-defined longitudinal stripes (Fig. 7). In contrast, most other Crendactylus species have relatively ‘clean’ longitudinal lines with possibly the exception of C. tuberculatus sp. nov. (Fig. 4 D). It is likely this broken colour pattern may be beneficial for camouflage owing to this species’ ground-dwelling habits. In contrast, the striped patterns in other Crenadactylus taxa are likely beneficial to species that climb in spinifex clumps and are likely convergent with the phasmid geckos in the genus Strophurus Fitzinger which also occur in spinifex.